With the development of information and communications technology, a variety of security systems are required. Financial transaction systems of banks require a customer's identification information, and fields of development of new technologies, such as research laboratories, also require improved security. Recently, due to these demands for improved security, various security technologies are being developed. As unique identification information of a user, various information for identifying the user, such as the user's voice, handwriting, etc., as well as a password arbitrarily set by the user is being used.
Lately, iris information is being used as identification information of a user, and security technology employing iris information is being developed. Because an iris is a physical feature of an individual user and causes no worry about loss or forgetting, iris authentication technology is attracting attention in terms of convenience. However, when an iris is artificially copied, a loss of usefulness as unique information of a user may be a problem.
Therefore, to compensate for existing user authentication technology employing an iris, there is an increasing need to use information on a sclera region around an iris as meaningful information. In particular, a sclera region has a brighter color than an iris, and changes in its color and brightness may be easily detected. Therefore, it is possible to detect a change of blood flow in a sclera, and a method of acquiring biometric information, such as a pulse, etc., through information on the change is proposed.